Index: uspace/lib/c/generic/io/printf_core.c
===================================================================
--- uspace/lib/c/generic/io/printf_core.c	(revision 7e1f9b7138c76a3ff70800594a3cae2de37a1c43)
+++ uspace/lib/c/generic/io/printf_core.c	(revision 9ac2013bb53c62688dcd0e2009ddb5c40df48cc1)
@@ -82,5 +82,6 @@
 	PrintfQualifierLong,
 	PrintfQualifierLongLong,
-	PrintfQualifierPointer
+	PrintfQualifierPointer,
+	PrintfQualifierSize
 } qualifier_t;
 
@@ -552,7 +553,8 @@
  *  - ""   Signed or unsigned int (default value).@n
  *  - "l"  Signed or unsigned long int.@n
- *         If conversion is "c", the character is wchar_t (wide character).@n
+ *         If conversion is "c", the character is wint_t (wide character).@n
  *         If conversion is "s", the string is wchar_t * (wide string).@n
  *  - "ll" Signed or unsigned long long int.@n
+ *  - "z"  Signed or unsigned ssize_t or site_t.@n
  *
  * CONVERSION:@n
@@ -736,4 +738,9 @@
 				}
 				break;
+			case 'z':
+				qualifier = PrintfQualifierSize;
+				i = nxt;
+				uc = str_decode(fmt, &nxt, STR_NO_LIMIT);
+				break;
 			default:
 				/* Default type */
@@ -763,5 +770,5 @@
 			case 'c':
 				if (qualifier == PrintfQualifierLong)
-					retval = print_wchar(va_arg(ap, wchar_t), width, flags, ps);
+					retval = print_wchar(va_arg(ap, wint_t), width, flags, ps);
 				else
 					retval = print_char(va_arg(ap, unsigned int), width, flags, ps);
@@ -849,4 +856,8 @@
 				precision = size << 1;
 				number = (uint64_t) (uintptr_t) va_arg(ap, void *);
+				break;
+			case PrintfQualifierSize:
+				size = sizeof(size_t);
+				number = (uint64_t) va_arg(ap, size_t);
 				break;
 			default: